Batteries
8 min read

Solar battery storage: the expert guide

Last updated on 22 February 2024

In this guide, we run through all the basics of solar battery storage, including how it works, all the benefits, and maintenance.

Photo of author Charlie Clissitt

Written byCharlie Clissitt

A solar battery with a pale blue background and a yellow booklet in the foreground

🔋 Solar batteries store up your solar panels' electricity when you're not at home to use it

⚡ Batteries charge up in the daytime and are ready to be used in the evenings

🪫 They typically last around 10-12 years

Looking to take control of your energy bills? By investing in solar panels with battery storage, you’re maximising the amount of clean electricity that you can use at home.

In this guide, we’ll run through all the basics of solar battery storage, including how it works, all the benefits, and maintenance. 

Knowing just a little bit about the different tech involved in solar batteries can help you make an informed choice and also maximise the life of your battery, should you decide to buy one.

To discover how much a solar & battery system could save you on your energy bills, click the button below and answer a few quick questions.

How do solar batteries work?

Picture this – the sun's up, and it's shooting down its rays full of energy. Your solar panels, basking in the glory of the sun, catch this energy and convert it into electricity through a nifty process known as the ‘photovoltaic effect’. 

When solar panels produce electricity, people must be in the house at that very moment in order to use it, otherwise it gets sent to the grid. However, if you add a battery, the electricity can be stored up, ready to be used later on in the day or overnight. 

Most batteries are sized according to a particular household, and it’s healthier for them to be filled up and discharged on a very regular basis. So if you want your battery to last a longer time, it makes more sense to fill it up and empty it on a daily basis, rather than filling up an enormous battery over several days and discharging it slowly. 

Although, it’s important to mention that most solar batteries should never be fully emptied, as this is bad for them. Batteries come with a ‘depth of discharge’ (DoD), which is given as a percentage (usually around 80%).

What are the benefits of solar batteries?

There are two main advantages to adding a storage battery to your solar panel system: lower electricity bills and reduced carbon footprint. Allow us to go into a little more detail...

1. Lower electricity bills

Solar panels cut your electricity bills in two ways: you buy less from the grid, and you also sell your excess electricity to the grid. Add a solar battery, and you’re buying even less from the grid. 

Obviously this means you’re selling less electricity to the grid, but in most cases the tariff you get paid for your extra electricity is less than the amount you pay the grid to buy electricity. One very appealing exception is the Intelligent Octopus Flux tariff, which typically pays around 26p per kilowatt-hour (kWh) at off-peak times and around 34.5p per kWh at peak times. 

You can also do some pretty clever things with a battery in order to maximise your savings. With smart batteries, you can automatically buy up additional electricity when it’s cheap, then discharge the battery and sell the electricity back to the grid when it’s expensive. Fortunately, the Octopus Intelligent Flux tariff is programmed to do this all for you.

A battery essentially means you're getting more from your solar PV system, which is pretty important given the high upfront cost of solar.

2. Reduced carbon footprint

Solar is a wonderful green solution, and it’s obvious that powering your life from the sun is greener than using the grid which still relies on a lot of fossil fuels. If you add a solar battery to your solar panel system, you’re relying even less on grid electricity. 

But what about the carbon that gets released from the factories making panels and batteries?

Well, just like the financial payback time, there’s a ‘carbon payback period’ too. The exact length of time depends on a lot of factors, but it’s typically around 1-4 years for solar panels.

For batteries, it’s a similar time range, sometimes as low as one year.

As a rough guide, if you keep your system for four years, you’ll be saving a lot more CO² than the amount that was released when your panels and battery were made.

What are the different types of solar battery?

There are two main types of solar battery commonly found in residential properties: lead-acid and lithium.

Lead-acid batteries: old tech, still used

If you’ve ever popped open the bonnet of their car, you’ll recognise the big heavy chunk of battery surrounded by engine parts. That’s a good old fashioned lead-acid battery.

Lead-acid batteries have also historically been the go-to choice for solar energy storage. They’re available in any car parts shop and are cheap.

Despite being a lot more affordable than lithium-based batteries, they don’t provide the best return on investment. That’s partly because you can’t actually use their whole capacity, and also because they wear out more quickly. So while they were a solid workhorse choice for years, you wouldn’t want to install one today.

Lithium batteries: efficient & safe powerhouses

Lithium based batteries are found in your smartphone and laptop, where they’ve gained popularity due to their lightweight design and impressive energy density.

Getting a bit more into the details, they're typically Lithium-Ion or Lithium-Polymer. But there’s actually a lesser known tech called Lithium-Iron-Phosphate, or LiFePo⁴ for short. 

Now there’s a couple of reasons that you want LiFePo batteries in your house and not the other kinds of lithium.

One: you know how airlines are a little touchy about you bringing laptops on board? It’s because they have a sneaky habit of catching on fire. Not something you ever want in your house. That’s where LiFePo comes in - it’s infinitely safer. That’s one of the reasons we only use this type of battery at Sunsave.

Another bonus is that they last a lot longer; with LiFePo, your battery usually comes with a 10-year warranty. 

A couple more advantages of lithium batteries over other types include:

  • High depth of discharge: This allows you to use more of the stored energy before needing to recharge.
  • Compact size: Their small footprint makes them an attractive option for homeowners with limited space.
  • They work well at different temperatures: other kinds of batteries stop working properly if it gets too hot or cold (-20°C to 60°C).
  • More robust: other kinds of batteries do weird things if exposed to pressure, punctures, or heat. LiFePo⁴ batteries are much less likely to have issues.
  • Built-in overcharge protection: they protect themselves from getting ‘too charged’, which can be an issue for other technologies.

Plus, LiFePo is the most eco-friendly option, compared to other kinds of batteries where:

  • Cobalt mining has been linked to human rights violations and environmental degradation.
  • Nickel can be toxic when released into the environment during production or disposal processes.
  • By choosing LiFePO4 batteries for your solar panel system, you're supporting an industry that prioritises sustainability and responsible practices.

Do solar batteries require any maintenance?

When calculating the overall cost of your solar battery storage system, it's vital to factor in routine maintenance expenses. These essential upkeep tasks include:

  1. Periodic inspections by a professional technician: Regular check-ups by a skilled expert will ensure your system is running smoothly and efficiently.
  2. Battery replacements: Depending on the type and usage, solar batteries typically need to be replaced every 10-12 years. This long-term investment ensures optimal performance.
  3. Minor repairs or component replacements as needed: Like any complex system, occasional repairs or part replacements may be necessary. Keeping your system in top shape ensures it continues to operate flawlessly.

While considering these maintenance costs, it's also crucial to get a workmanship warranty. This warranty provides invaluable coverage against any errors or issues that may occur during installation or system performance. It's your safety net, offering peace of mind and financial security. Not all solar installers provide this, but every Sunsave install comes with a full workmanship warranty.

Where’s the best place to install a solar battery?

When it comes to finding the best place to install your solar battery storage system, we understand that you want a hassle-free process from start to finish. Our expert team is here to guide you through every step, ensuring a seamless experience.

Before making any decisions, we'll assess your property's available space, considering crucial factors such as:

  • Accessibility: It's important to have easy access to the system for maintenance and inspections. Our installations prioritise convenience and practicality.
  • Ventilation: To maintain optimal performance and prevent overheating, proper ventilation is key. We'll ensure that your system is placed in a location that promotes efficient airflow.
  • Protection from extreme weather conditions: We know the importance of safeguarding your investment. Our professional installers will identify a suitable location that shields your solar battery storage system from excessive moisture, extreme temperatures, and other potentially damaging environmental factors.

Rest assured, our team of experts will work closely with you to determine the most suitable location based on your property's unique characteristics. We understand the significance of a well-placed and well-protected system, and we're committed to providing you with a hassle-free and efficient installation process.

Can you add a solar battery to an existing solar panel system?

It’s certainly possible, but before upgrading an existing photovoltaic system with battery storage, you should consider several factors:

  • System size: The size of your current solar panel installation will determine how much excess energy you generate that can be stored in a battery. You'll need to calculate this amount based on historical data or estimates from professional installers.
  • Energy consumption patterns: Analysing how and when you consume electricity will help identify peak usage times when stored energy could be utilised most effectively.
  • Available space: Installing a new battery storage system may require additional space for the battery itself, as well as any necessary wiring or components. Ensure you have adequate room for installation and maintenance.

System size, energy consumption patterns, space considerations – it's enough to get your head spinning, right? Well, guess what? You don't have to go it alone.

Our friendly team at Sunsave is here to guide you through this adventure, making it as simple and stress-free as possible. And they'll do it all in a straightforward, jargon-free way that puts you at ease.

Summary

If you’re thinking of getting yourself a solar-plus-storage system, we're here to provide the guidance you need. You can leave the intricate details to our friendly team of experts, all certified and renowned for their great customer service.

And don't fret about disruption or stress; we have cutting-edge 3D imaging software that allows us to carry out all necessary checks remotely. It's like having a solar energy expert right in your living room, but without the awkward small talk or tea-making obligations. We're all about taking the hassle out of the equation.

Whether it's understanding the intricacies of roof suitability, the legalities of planning permission, the options for financing, or the latest on smart home energy management systems and electric vehicle integration, we're on hand to provide clear, detailed explanations.

Solar batteries: FAQs

Can I ‘go off grid’ with solar and batteries?

There are a few folks out there who like the idea of 'cutting the cord' and living a totally off-grid lifestyle, relying solely on solar power. That's definitely possible, and it's an exciting concept for those who enjoy a cabin-in-the-woods vibe. 

However, it's not a common path for most UK homeowners and is unlikely to offer the best financial return. That’s because you’d need a much bigger (and more expensive) solar & battery system to cover yourself in winter, but it’d be far too oversized in the summer. 

You can however get solar batteries installed in such a way that allows you to keep the lights on during a power cut - but this isn’t quite the same as being fully ‘off-grid’.

How long do solar batteries typically last?

Solar batteries usually have a lifespan of 10-12 years. That doesn’t mean they will be completely useless by that point, but they won’t be able to hold as much charge as they originally did, and there’s a chance that the control circuits will give up the ghost.

The real lifespan is based on ‘cycles’ - e.g. how many times you charge it up and then use all the juice. So if you buy a battery for a holiday home, for example, where it’s not used everyday, it’ll last many more years.

Make sure to choose high-quality products from reputable manufacturers for longer-lasting performance.

Can I add battery storage to my existing solar panel system?

Yes! Adding battery storage to an existing solar panel system is possible and can help you store excess generated electricity for later use or during power outages.

Are there any UK government incentives for installing solar batteries?

Yes, the Smart Export Guarantee (SEG) is a UK government scheme that pays you for exporting excess electricity generated by your solar-plus-battery system back to the grid.

For the latest best SEG rates, check out our article.

VAT is also cut until 2027, while in Scotland, there’s also the option of a government-backed zero interest loan.

Copyright © 2024 Sunsave

Sunsave Group Limited (company number: 13741813) and its affiliates, Sunsave UK Limited (company number: 13941186) and Sunsave Energy Limited (company number: 13952135), together trading as “Sunsave”, provide renewable energy systems and finance and are registered at 23 Ansdell Terrace, London, W8 5BY. Sunsave Energy Limited (FRN: 979494) is a lender authorised and regulated by the Financial Conduct Authority. Sunsave UK Limited (FRN: 977566) acts as a credit broker and can introduce you to a panel of lenders for the purpose of arranging finance. Sunsave UK Limited is an appointed representative of Product Partnerships Limited (FRN: 626349) which is authorised and regulated by the Financial Conduct Authority and registered at Suite D2 Josephs Well, Hanover Walk, Leeds, LS3 1AB.